Primers are designed to be used in ammunition, fuze systems, or initiating systems for the purpose of converting mechanical, electrical, optical or thermal impetus into chemical energy output. Such primers are typically composed of a cup holding an energetic formulation, foiling or sealing device, and an anvil/closure disc.
The process of primer fabrication involves mixing raw chemicals into an energetic formulation, dispensing the energetic formulation into conventional primer hardware, drying the energetic formulation to remove processing solvents and moisture, inserting a foil which both prevents dusting of material during processing and contains material in cup during handling and transport, consolidation of mix, anvil insertion, and sealing, if necessary, to protect the primer from moisture absorption and to contain the material during handling and transport. Current primer manufacturing processes are labor intensive, lack consistency, inefficient and presents safety risks to operators during assembly. The process requires preparation of the energetic primer formulation which is conducted by adding individual constituents to a planetary mixer and utilizing shear mixing at controlled speeds for a set duration of time to achieve the desired consistency. Solvents are utilized during the mixing process to ensure consistency of the mixture and increase safety during handling. Maintenance of minimum solvent concentrations greatly reduces the materials' initiation sensitivity to impetuses such as friction, impact or electro-static discharge (ESD). These solvents are typically used in an open mixer which is exposed to ambient air where evaporation is hard to control and solvent percentages are difficult to maintain or analyze. Maintaining the moisture content for safety purposes also affect the consistency of the primers as the current formulation is loaded volumetrically. The energetic mixture is then spread by hand to disseminate into fill quantity by volume of the primer hardware. Transfer of the energetic material into the primer hardware is by an imprecise method which does not verify transfer. Foil and lacquer is placed over the energetic mixture which is consolidated and the anvil inserted over the assembly. After the components are assembled, the primer is dried for an extended period of time before it is operable. Each step in the process is completed either manually or by hand operation using semi-automated equipment.
The current process outline above fails to provide consistent testing and verification for quality control purposes during each step of the process. Quality control is subject to operator training who is required to visualize hundreds if not thousands of parts that are smaller than the diameter of a dime. The human operators are exposed to safety risks inherent with operation of energetic materials. Such risk may be minimized by controlling the quantity of energetic formulation in the process area and manually maintaining moisture levels of the energetic formulation and processing equipment. However, determination of the quantity of moisture to add is typically based on visual inspection and not a quantifiable metric.
Given the drawbacks noted above, a need exists for more efficient, consistent and safer primer manufacturing methods. The invention disclosed herein provide methods to automate the primer manufacturing process that is not only more controllable, tailorable and repeatable but also increases the safety of operators over current methods by enabling stand-off distances and reducing potential operator error.